[hatzie]

Originally Posted by Gregski

I upgraded my 74 no Tach to a cluster from a 76 I think with Tach, here's what I learned

1. Used Tachs don't work, as a matter of fact all old gauges don't work, or work poorly, I would recommend a brand new one, or even a good quality aftermarket one if I was to do it again

2. I also wanted to retain my old speedo with the new Tach and guess again, can't or at least not with some doing, the non Tach Speedo is different believe it or not than the Speedo that comes with the Tach I think the front plate facia won't fit, you would need to do a swaparoo not sure it is worth it, I may be attempting it cause my newer used Speedo stopped working, see #1 above

1 You can fix the old Tachs by repairing the circuit board. Fix Squarebody GM Truck Tach

Wilcox Corvette among others sell a replacement circuit board.
More discussion on this here --->67-72 Chevy truck forums. 7K 73-87 tachs

2 There are not with-tach and without-tach speedometers. You can move your speedometer to the tach cluster housing. I've done it. It fits fine.
The tach doesn't drop into the large fuel gauge cluster housing. You need a Tach cluster housing or extensive modifications to your non-tach gauge housing. The tach printed circuit is also quite different to accommodate the connection on the back of the housing. It also must accommodate the small fuel gauge connection in the lower LH part of the pod.
You can get into trouble with the warning lamp slot in the bottom of the tach and the speedometer. It's possible to have 0, 1, or 2 warning lamps in the bottom of both 5" gauges.